The 3rd Generation Partnership Project (3GPP) has recommended a network scheme it terms “Long Term Evolution” (LTE). In an LTE network, all communications are carried over an Internet Protocol (IP) channel from user equipment (UE) to an all-IP core called the Evolved Packet Core (EPC). The EPC then provides gateway access to other networks while ensuring an acceptable Quality of Experience (QoE) and charging a subscriber for their particular network activity.
The 3GPP generally describes the components of the EPC and their interactions with each other in a number of technical specifications. Specifically, 3GPP TS 29.212, 3GPP TS 29.213, and 3GPP TS 29.214 describe the Policy and Charging Rules Function (PCRF), Policy and Charging Enforcement Function (PCEF), and Bearer Binding and Event Reporting Function (BBERF) of the EPC. These specifications further provide some guidance as to how these elements interact in order to provide reliable data services and charge subscribers for use thereof. Note that the PCRF function is provided by a PCRF node (PCRN) and that the terms PCRF and PCRN are often used interchangeably. In this document, PCRF can refer to the node that provides this function.
When General Packet Radio Service (GPRS)-compatible access networks participate in a mobile network end-to-end connection with a PCRF node (PCRN) as a policy decision maker, multiple network topologies are possible, including a topology where a Packet Data Network (PDN) gateway (or “P-GW”) is directly connected to a Serving GPRS Support Node (SGSN) via a Gn/Gp interface. This topology essentially makes the P-GW a combination node: On a downstream connection to an SGSN, the P-GW has Gn or Gp interface; on an upstream connection to the PCRN, it appears to the PCRN as an Evolved Packet System (EPS) P-GW, rather than a Gateway GPRS Support Node (GGSN).
In view of the foregoing, it would be desirable to provide a Policy and Charging Rules Node (PCRN) implementing a PCRF capable of distinguishing a P-GW combination node network topology from a traditional GGSN gateway and from a P-GW connected via a Serving gateway (S-GW) to a SGSN, in order for PCRF to be able to make appropriate policy and Policy Control and Charging (PCC) rule decisions